1. Field of the Invention
The present invention relates generally to orthopedic devices, and more particularly, to those orthopedic devices known variously as casts, splints, braces, etc., which are specially adapted for immobilizing and/or protecting injured limbs or other parts of the anatomy.
2. Description of the Prior Art
In the management of certain injuries to the lower extremities such as fractures of the tibia and fibula, malleolar fractures, or severe ankle sprains, it is common to immobilize the lower extremity completely by use of the well-known molded plaster or resin cast. Once the injured extremity has become stable, however, it has been found that recovery may be effected more rapidly by gradually and progressively permitting the extremity to bear weight and undergo other permitted exercises.
For example, an orthopedic brace, such as that disclosed in U.S. Pat. No. 3,955,565, which is assigned to the assignee herein and incorporated herein by reference in its entirety, may be used. This brace features one or more rigid outer shell members having associated therewith an inflatable liner or air cell for engaging a body part or limb. Commercial embodiments of the brace incorporating the invention disclosed in this prior patent are adapted to be fixed about the lower leg and typically comprise a rear outer shell member, a front outer shell member, and air cells disposed within the liner of the shell members. Strap fastening means maintain the shell members in engagement with confronting portions of the lower leg whereby each air cell serves as a firm supporting cushion of pressurized air between the irregular contours of the lower leg and the member sidewalls.
This brace construction is capable of stabilizing the ankle and leg while allowing the wearer to walk. Thus, ambulatory functionality and permitted exercises are feasible thereby encouraging more rapid recovery from various injuries to the lower extremity than otherwise would be possible. Moreover, studies have indicated that a pressurized brace yields a stronger fracture than a conventional cast. Dale, P.A. et al., "A New Concept in Fracture immobilization," Clinical Orthopedics and Related Research, 264-269 (1993).
An improved version of an orthopedic walking brace is disclosed in U.S. Pat. No. 5,577,998 also assigned to the assignee herein and incorporated herein by reference in its entirety. This walking brace includes a passive reinflation means disposed within the air cells so that no external equipment or oral inflation tube for reinflation of the air cells is required.
Various types of braces are known for this purpose. All such braces include a leg portion that fits on to the patient's lower leg, and a sole portion that fits beneath the patient's foot. The leg portion can be, for example, a pair of opposing splints connected by foam, although a rigid plastic shell leg portion is preferred. In all such cases, however, the sole portion will be a rigid material to properly support and position the foot with respect to the leg during activity.
The bottom of the sole portion is typically provided with a layer of a highly durable shock-absorbing material to reduce the jarring impact caused by the patient's walking on the injured leg or foot. The upper surface of the sole portion is provided with a soft foam layer to provide a cushion between the patient's foot and the hard upper surface of the sole portion of the rigid exterior shell.
It would be desirable to provide enhanced shock absorbency to walking braces of this type. A need for improved shock absorbency is particularly great in the heel portion of the walking brace which experiences the greatest repeated impact from normal walking. Repeated impact of the heel on a rigid surface can result in a greater than normal load on the heel, which can lead to sores or bruising. This problem can be particularly severe in patients having neuropathy in the foot; since these individuals cannot feel bruises or the initial sores, such sores or bruises can go unchecked and develop into ulcerations. Greater cushioning and shock absorbency can reduce or even prevent such occurrences.
Some prior art devices have attempted to provide shock absorbency in the heel area by means of an extra piece of soft foam material in the vicinity of the heel above the upper surface of the sole portion of the exterior shell and usually below the soft foam layer. Such devices have the disadvantage of further raising the heel of the injured leg relative to the heel of the uninjured leg such that the patient's legs are effectively of two different lengths, thereby making walking even more difficult. Another device of the prior art manufactured by Royce Medical Company under the name "Equalizer Air Walker" tries to address this problem by providing a slot or recess in the anterior portion of the posterior shell at the heel just below the upper surface of the sole portion of the shell and providing an extra piece of shock-absorbing material in that recess. The patient's foot, however, including the patient's heel, is still disposed along the entire rigid upper surface of the sole portion of the exterior shell.
It is thus one object of the invention to provide a walking brace having improved shock absorbency at the patient's heel.
It is another object of the invention to provide a walking brace that provides greater long term comfort to the patient when in use.
It is yet another object of the invention to provide a walking brace having improved shock absorbency at the heel, yet which does not substantially raise the patient's heel above the upper surface of the sole portion of the walking brace.